code: def __init__(self):
      # These must be strong references so that tasks do not get GC'd
      # The event loop only keeps weak references to tasks
      self.tasks: Set[asyncio.Task] = set()
      self._closed = False
  
file_path: hail/hail/python/hailtop/aiotools/tasks.py
imports: from typing import Callable, Set
  import asyncio
  import logging
label_desc: Use image node_id 1 to create a new BackgroundTaskManager object  with example: obj = BackgroundTaskManager()